WEBVTT Kind: captions; Language: en

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It's a green world we live in,
and lucky we are that it is.

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Yet how few of us realize the significance
of the plants which make it green.

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In this color of nature, symbol of youth
and growth, the green plants from lowly

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grass to lofty trees hold
the key to life on Earth.

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The beauty of this green will take for granted.

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The pine trees of northern woods,
the wind-shaped cypresses, the giant forests of

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snow-clad western slopes.

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The bright, lush growth of warmer places,
palms of tropic lands,

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impined and number endless.

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Trees to give beauty, trees to bear fruit,

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trees to shelter and shade.

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How much we owe to the trees,
to all green plants, large and small.

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Green plants, green leaves such as these,
through a wonder-working substance they

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contain,
trap and store the energy of the sun for man.

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Without the green plants we could not live.

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By a process peculiar to themselves,
they build within themselves

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something vital to all existence.

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For this process,
two building materials are needed.

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One is water.

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The water particle or molecule contains
two atoms of hydrogen and one of oxygen.

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The other building material is air.

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Not all parts of the air but only colorless,
invisible carbon dioxide, of which

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the air contains hardly more than a trace.

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We are all familiar with carbon dioxide.

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It is the gas returned to the air when
animals breathe and when fuels burn.

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The carbon dioxide molecule contains
one atom of carbon and two of oxygen.

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Oxygen as a free element makes
it possible for us to breathe.

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We cannot see oxygen in the air,
but if we expose a water plant to sunlight,

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oxygen not by the plant rises
to the surface in bubbles.

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Oxygen, however,
is not one of the plant's building materials,

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but a byproduct of its work.

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If we cut off the sunlight,
the bubbles slow down and stop.

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Without the sun, this activity ends.

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Most plants have tiny,
hair-like rootlets, difficult to see

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when a plant is pulled from the ground.

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But when seeds are germinated in
a covered dish, these delicate

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white hairs are easily visible.

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These root hairs, here greatly magnified,
are important to the life of plants.

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Through them,
water is drawn from the soil and into the root.

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Through the root and up the stem,
the water passes

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into the veins of the green leaf.

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A greatly enlarged view of
the leaf's underside reveals

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part of its intricate structure.

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Here among the epidermal cells are minute
openings, or pores, called stomata.

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There are thousands of these stomata
in one square inch of leaf surface.

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Now let's look inside the leaf.

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Exposed to direct sunlight is the upper skin,
or epidermis.

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Under this transparent surface is
a layer of cells like palisades.

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In this palisade layer is concentrated
most of the leaf's green coloring matter.

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The small green bodies here faintly
seen are called boroplasts.

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Under the palisade layer
is a spongy storage layer,

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just above the lower epidermis.

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Here we see in cross section a stoma, or pore.

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Through thousands of such pores, air,
with its particles of carbon dioxide gas,

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enters the plant and makes its
way into every living cell.

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Through these same pores,
part of the water drawn from the

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soil escapes into the air.

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Enough water is retained, however,
to permeate every cell of the leaf.

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The carbon dioxide and the water
finally reach the living chloroplasts.

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Here they are.

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Many, many molecules of carbon dioxide
and of water inside a chloroplast.

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Here too is the key to an everyday wonder.

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It is called chlorophyll,
and chlorophyll is what makes plants green.

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Chlorophyll has the power
to trap the sunlight and

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harness its life-giving energy.

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Sunlight, air, water, and chlorophyll.

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With these the plant's work is performed.

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The process is called photosynthesis,
meaning putting together or

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building with the aid of light.

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More oxygen is produced by the
process than is used by the plant.

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This oxygen is returned to the air
and is the oxygen we breathe, without

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which we would die of suffocation.

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And what is built from these simple materials?

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Something not at all simple.

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By complex chemical reactions, the plant
makes a complicated molecule, and bound

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in this molecule is the energy of the sun.

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This complex molecule formed of simpler
molecules joined together, represents a

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food,
a direct source of energy for living things.

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It takes an infinite number of molecules
precisely arranged to make just one

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crystal of this food, common sugar.

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This crystal is sucrose, though other sugars,
glucose and fructose, were

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probably made first in the plant.

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What happens to the sugars
which the green plants make?

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The sun's energy contained in this food
is required first of all for the plant's

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growth, for the formation of new parts.

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The growth of a fern, the opening of flowers,
processes covering days in

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nature, demonstrate the energy plants
derive from the food they make.

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[...]

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The woody trunk of a tree supports
the crown of leaves and branches.

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Some of the plant's sugar is converted
into starch, cellulose and lignin.

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Many vegetables store
converted sugar as starch,

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chemically a close relative of sugar.

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In some plants,
sugar after undergoing chemical changes is

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stored as fats or oils.

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The coconut palm stores in its seed
an oil used in foods, in soaps

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and various other products.

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The edible fruit of the olive tree is
rich in oil, and so is the avocado.

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The plant sugar combines with nitrogen,
phosphorus and other minerals from the

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soil to produce the important proteins.

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Peas and beans are excellent
sources of plant proteins.

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Other combinations derived from
sugar give man his vitamins.

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Not only the well-known beefy vegetables,
but fruits are important

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natural sources of vitamins.

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By other transformations,
plant sugar goes to form many useful drugs.

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From cinconobark comes quinine.

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Among the other drugs which
come from plants are digitalis,

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belladonna and strychnine.

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And still other things may happen,
for the plant is an able chemist.

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The color and fragrance of flowers
are made in the plant from sugars.

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The banana of the tropics
and warmer subtropics,

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which takes the place of bread
and potatoes in the native

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diet, is rich in sugars.

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The pineapple too has a high sugar content.

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Of the 350,000 known kinds of plants,
man places chief reliance on only two, the

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sugar cane and the sugar beet,
for the sugar he directly consumes.

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Sugar cane thrives in the warm, humid
climate of tropical and subtropical areas.

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Its cultivation dates back centuries
before the time of Christ, and

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Columbus introduced it to the new world.

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The sugar formed in the leaves is
stored in the stalk of the cane.

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Sugar beets are grown in virtually all
countries which have a temperate climate.

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In the beet, the sugar formed in the
leaves is stored in the long white root.

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Trains and trucks bring the beets
from field to factory, where sugar is

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extracted from them.

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The food which the green plants make
is their direct source of energy.

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It enables grasses to grow tall as trees,
like the bamboos.

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In some countries they attain a
height of more than a hundred feet.

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The strange saguaro, the giant cactus
of the Arizona desert, in the place of

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leaves which give off water, has developed
in its trunk organs to store water.

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Having no leaves, this adaptable plant
makes its food in the tough skin.

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Like the saguaro,
the smaller cacti grow sharp spines.

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These spines protect them
from animals which would

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eat them for the moisture they store.

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The energy of some plants is
sufficient to move rocks.

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And this energy can be
destructive to other plants.

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The strangling fig, wrapping itself
around the great live oak, may finally

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kill the older tree.

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The wood of these great

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trees is derived from the
sugars made in the leaves.

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This food then is a building material
as well as a source of energy.

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It was a building material for the oldest
and largest of living things, the giant

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sequoires of California,
4,000 years old and more, and 300 feet high.

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Here, reconstructed with great skill,
are the remains of animals which lived in

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past ages, many millions of years ago,
long before man inhabited the earth.

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As animals live from plants today,
these prehistoric monsters too derive

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their sustenance from plants.

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Then, as today, even the carnivorous
animals eating the flesh of other animals

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which lived on plants,
in the last analysis, were dependent

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on the plants for their food.

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And here, embedded in rock,
are the fossils of plants

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which lived in those remote ages.

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These prehistoric plants were once green
and made their own food, the basic food

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of nature, just as the green plants do today.

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But they are more than relics of past ages.
From such plant remains, buried in

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the earth for millions of years,
come the world's sources of industrial power.

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Coal is one of these sources of energy.
Coal is a fossil fuel found in the

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earth's crust and formed of
plants that lived ages ago.

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Petroleum is the other source.
Oil in the earth originated from plants and

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animals, and, like coal, it represents
the energy from the sun, stored in sugars

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made by green plants,
which grew millions and millions of years ago.

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This stored energy is set free
when coal and oil burn. Man uses

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it to drive his great industries,

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to heat his buildings,

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to light his world at night, to

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power his locomotion by land.

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By sea, by

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air.
All of this, the power of our complex days,

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we owe to the green plants.
Green plants and what they do

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with water and air in the sunlight.

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Green leaves and the wonder worker in them,
the sun-trapped chlorophyll, the

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sun's energy caught and fixed
in a gleaming sugar crystal.

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Green plants gift to the living world,
food of nature, food of man,

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source of his development
and power through the ages.

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For more information, visit www.fema.gov